Switchboard circuits



May 14, 1940.

P. J. RUNKEL 00.682

SWITCHBOARD CIRCUI'iS Filed Jan. 25. 1939 1 /117120 Jill/7Z6] INVENTOR ATTO R N EYS Patented ay 14, 1940 i UNITED STATESFPATENTOFFICE Philip J. RunkeLQ Stevens Point, Wis. Application January 23, 1939, seri ri 252,449

1 Claim. (01. 115-312): 1

My invention relates to electric circuits, and has among its objects and advantages the provi sion of an improved dimmer circuit particularly adapted to systems for controlling the current in theatre lighting circuits, floodlighting and the like.

In connection with switchboards, particularly in theatre lighting circuits and the like, it is com mon practice to permanently connect a. voltage control apparatus with each circuit in the switchboard. The cost of eachsuch control ap paratus far exceeds the cost of each circuit, and it is rarely thatthe voltage control apparatus of more than a minority of the circuits is being 15 operated at a given time. Only a comparatively few of the load circuits, after the dimming process, are left with their voltages at anything other than zero or. normally full voltage.

It Will thus beseen that any switchboard wherein each circuit is connected permanently 2 to. a dimmer which will alfect that circuit and none other, the ratio of the number of hours any one dimmer is used to the number of hours the switchboard is usedconstitutes a small frac.- 25 tion of the total time involved. Therefore, the

. dimmer facilities, which constitute a most eX. pensive part of the switchboard structure,;lie idle a great majority of the time.

Accordingly, an object of my invention is to provide a system wherein one dimmer may be transferred to any one of a numberof load cir-.- cuits when the voltage in that circuit is zero or full.

It is important that the dimmer facilities be so devised as to be insertable in or removable from a load circuit without affecting the lamps connected with that circuit. If the lamps in the circuit are full on, it must be possible to insert a dimmer into the circuit preparatory to dimming down without causing the lamps to blink, that is, to go off, or change intensity for even the smallest instant. Similarly, if the lamps in the load circuit are full off, itmust be possible to plug in the dimer without causing blinking.

5 This also holds true in connection with removal of the dimmers from the circuits. My circuit is so designed asto fulfill these requirements. More specifically, I make use of an auto-transformer dimmer circuit which may be plugged into 50 any one of the load circuits incorporated in the switchboard. The auto-transformer dimmer is rated at a maximum load capacity, and any load which is of a wattage not over the rated capacity may be used with it. In connection ,with resistance dimmers, such dimmers are rated for a certain wattage load. If the resistance dimmer is used with anylesser orgreater load, the result is that either the dimmer burns out, or the load does not dim completely or satisfactorily. For instance, if the resistance dimmer is rated at 5 2,000 watts, only a load of 2,000 watts may be fully controlled @by it. The steps of voltage change in the auto-transformer dimmer are practically nil, so that when the dimmer is used to control incandescent lamps, each of the steps composing any individual voltage change resulting from adjustment of the dimmer is indiscernible to the eyeas a step. This is not true of a resistance dimmer wherein the step is undesirably discernible. A furtherobject is to provide a, system of the type described inwhich the circuit facilities are exceedingly simple in their; construction, ar rangement and operation.

In the accompanying drawing:

Figure 1 isa fragmentary view of ,a switchboard illustrating my invention applied thereto; and v Figure 2 is a diagrammatic view of tW O Of the svlritchboard circuits and the dimmer circuit tapped into one of the circuits.

In the embodiment selected to illustrate my invention, I make use of a switchboard 50 which may be wired toprovide a plurality of identical circuits l2 and I4. Circuits l2and Hi areiden- 3O tical in construction and operation so that the descriptionof one will apply to both. Linewire I6 comprises the hot wire, while line wire it comprisesthe neutral wire. For the sake of convenience, the description will be directed largely to circuit M. Q

A wire 20 connects the wire lit with the terminal 22 of a load receptacle 24. The other terminal 26 of the load receptacle is connected with the terminal 28 of a double-throw switch 30. Switch 30 comprisesblades 32 and intercon riected by an insulated linkjSfi. Blade 32 is electrically connected with the terminal 28 and is arranged to be moved into conducting relation with the terminal 38 of the switch 30, which terminal is connected with the wire 58 through the medium of a wire A0. Blade 34 may be moved into conducting relation with a terminal 42 associated a wire l l, and the blade is electrically related to-a terminal Mi connected with a'wire 48 connected to the wire It, as at 50.

Load wires Hand 54 terminate in prongs 50 and 58 carried by ajplug 60. Prongs 56 and 58 are adapted to be moved into conducting relal tion with theterminals 22 and 26, respectively.

Thus the circuit may be closed through the load 62 by moving the blade 32 into conducting relation with the terminal 38.

Wire 44 is connected with the terminal 64 of a dimmer receptacle 66. The wire 68 connects the terminal 28 of the switch 38 with the terminal 26 of the load receptacle 24. Terminal 78 of the dimmer receptacle 66 is connected with the wire 68 through the medium of a wire 12. According to Fig. 2, my dimmer circuit 14 comprises a wire 16 connected withthe prong. 78 of the plug 89, which prong is arranged tobe moved into electrical relation with the terminal 64 of the dimmer I receptacle 66. The opposite end of the wire 16 is connected at 82 with a coil 840 fan-auto- Y transformer dimmer 86. Wire l8 is connected with the coil 84 at 88, while the prong 90 asso ciated with the dimmer plug 88 is electrically.

connected at 92 with a sliding tap 94 through the medium of a wire 95. Rotation of thesliding tap may be made through the medium of a knob 97.

Coil 84 comprises wire woundlin the form. of a helix so as to set up, when current passes through it, an electromagnetic impedance to that current, such that the voltage potential from full, at the point 62, gradually drops to zero, at the point 88. The sliding tap 6.4 is so arranged as to make contact with the coil 84 at any of a large number of closely spaced points. Thus the potential at any point in the coil may be tapped through the medium of the sliding tap.

Switch 36, when positioned as illustrated in circuit I4, may be said to be in the dimmer position, while switch 36, as-illustrated. in the circuit l2, may be said. to be in the load position. With the switch 38 adjusted according to the circuit l2, there isa full potential of 110 volts across the load 62, but when positioned according to the circuit l4, there is a potentialof zero across the load. The auto-transformer dimmer 86; includes a dial 96 having graduations 98 reading from zero to one hundred. Knob 91 carries a pointer I80 which determines the position of the slider 94 on the coil 84. V

With the switch 30. inits dimmer position and the plug 88 connected with the receptacle 66, assuming that the slider 94 is inits zero position, the circuit through the load is broken. In other words, we may trace the-incomplete circuit as follows: from wire l6 towire 20, terminal 22, prong 56, wire 52, load 62, Wire 54, prong 58, terminal 26, wire 68, terminal 18, wire'95, slider 94, zero connection 82, wire 16, prong 18, wire 44. terminal 42, blade 34; terminal 46 and wire 48 connected with the wire l6. It willthus be seen that the load is fully off. In turning the slider 94 to the other end of the coil 84, the circuit is traced as follows: from wire 5 to wire 26, terminal 22, prong 56, wire 52, load 62, wire 54, prong 58, terminal 26, wire 68, terminal 76, prong 90, wire 95, slider 94 and back to the wire I8. Thus the circuit through the load will be closed.

Neutral wire I8 is connected with one end of the coil 84, while the opposite end of the coil is connected with the hot wire l6 as follows: wire 48, terminal 46, blade 34, terminal 42, wire 44, terminal 64, prong i8 and wire 76 leading to the connection 82 with the coil. 'Tracing the circuit from connection 82 through wire 16, prong l8, terminal 64, wire 44, terminal 42, blade 64, terminal 46, wire 48, wire 28, terminal22, prong 56. to wire 52, we find that one end of the coil is connected with one side of the load. Tracing from connection 92 through wire 95, prong 98, terminal 10, wire 12, wire 68, terminal 26, prong 58 and to wire 54, we find that the other end of the load is connected with the slider 94. Thus the four connections necessary to the proper operation of the auto-transformer dimmer are established. Therefore, as the slider 94 is turned from its zero position to its full on position, the load will be gradually dimmed up from full oii to full on. I

Similarly, we may turn the slider from its full on position, to its zero position for gradually dimming out the load. Slider 94 may be adjusted to any one of many positions for dimming up or dimming out the load circuit in variable degrees. Switch 38 may be adjusted to its load position, during which adjustment there is a moment when both terminals 38 and 42 are comi pletely. disconnectedfrom their respective blades 32 and 34. For the sake of illustration, let us assumethat the slider 94 is in itsfull on position. With both terminals 38 and 42 momentarily disconnected from their respective switch blades, the circuit may be traced as follows: from wire l6 through wire 26, terminal 22, prong 56, wire 52, load 62, wire 54, prong 58, terminal 26, wire 66 wire 72, terminal [6, prong 96, wire 95, slider 94 and back through l8. Thus the circuit will remain closed notwithstanding the open position of the switch 38. With the blade 32 contacting the terminal 38 the terminal 42. is disconnected from the circuit. Thus the dimmer plug 36 may be removed and the circuit through the load will be complete. The dimmer plug 69 may be disconnected with no consequent blinking in the load. circuit. The same may be said of my circuit when disconnecting the dimmer plug 88 with the slider 94 in its zero position. If it is desired to leave the load either full on or full ofi upon inserting or removing the dimmer plug, the slider must be adjusted to its proper on or off position.

With. the switch 38 in the, dimmer position and the plug 88 connected with the receptacle 66, the load will correspond to whatever point is indicated by the graduations 98 which determine the location of the slider.

Briefly stated, the general operation may be stated as follows: toturn the load. full on, the

switch 36 is thrown to its load position. In turnmg the load fully ofi, the switch is thrown to the dimmer position, i. e., the position illustrated in circuit M. In dimming theload up-gradually to full on, the plug 88 is connected with the receptacle 66 with the switch 38 in its dimmer position. The slider 94 is then turned to its full on position. To leave the load fully on and disconnect the dimmer for other purposes, the switch 38 is thrown to its load position'and theplug 88 removed. In dimming the load down gradually to full off, the plug 89 is connected with the receptacle 66, the switch 39 moved to its dimmer position and the slider 94 Thus the load may be left fully oil at this time by merely removing the plug 86,. To dim the load gradually up to seventy-five per cent, as an example, the plug 86 is connected. with the recepturned to its zero position.

tacle 66 with the switch 36 in its dimmer position i and the slider 94 adjusted to the graduation indicating seventy-five per cent delivery.

Receptacle 66 is of the two-pole polarized type, while the plug 80 is also polarized. The plug 89 can be connected with the receptacle 66 in one way only. With the plug 88 disconnected, the

prongs of the plug cannot lead anywherev but to a the neutral wire I 8. When the circuit is installed in a switchboard, the only exposed carriers of current are these, which are dead at all times at which they are exposed. Thus the dimmer circuit may be manipulated with complete safety.

Without further elaboration, the foregoing will and second terminals associated with each of said load circuits, the first terminals being electrically connected with their respective fourth wires, fifth wires connecting said second terminals with said first line wire, a switch in each of said fifth wires for opening and closing that wire with respect to said first line wire, each switch in said fourth wires being operatively connected with the switch 5 in said fifth wire of that load circuit in such manner as to break the fourth wire when said fifth wire is closed and vice versa, a dimmer circuit in cluding an auto-transformer having a wired connection with said second wire, thirdand fourth 10 terminals, a wire connecting the third terminal with the wiper element of said auto-transformer, a wire connecting the auto-transformer with said fourth terminal. and said third and fourth terminals being adapted for selective connection with 15 said first and second terminals of each load circuit for controlling thelight intensity thereof.

PHILIP J. RUN KEL. 

